Pressure equalization means between compartments in a puffer circuit interrupter

ABSTRACT

A puffer type fluid blast circuit interrupter having a gas tight casing subdivided into two compartments. In the opened position of the interrupter the two compartments communicate freely to permit a rapid equalization of the pressures in the whole casing. An escape valve opens in the case of an excess of pressure in one compartment to allow escape of pressure into the other compartment.

I United States Patent [191 [111 3,733,452 Strippoli et al. May 15, 1973 [54] PRESSURE EQUALIZATION MEANS [56] References Cited BETWEEN COMPARTMENTS IN A UNITED STATES PATENTS PUFFER CIRCUIT INTERRUPTER 2,957,063 10/1960 Leeds ..200/l48 A 3,527,912 9/1970 Jaillet ..200/148 A [75] Inventors: Francois Strippoli; Guy Combet, 3,621,171 11/1971 Yoshioka ..200/l48 A both of Grenoble, France FOREIGN PATENTS OR APPLICATIONS [73] Assignee: Merling Gerin, Societe Anonyme,

Grenoble France 384,673 2/1965 Switzerland ..200/148A [22] Filed: Feb- 5, 1971 Primary ExaminerRobert S. Macon [21] Appl. No.: 112,887 Att0mey-Stevens, Davis, Miller & Mosher [57] ABSTRACT [30] Foreign Application Priority Data A puffer type fluid blast circuit interrupter having a gas tight casing subdivided into two compartments. In Feb. 16,1970 France ..7005501 the Opened position of the interrupter the two partments communicate freely to permit a rapid equalization of the pressures in the whole casing. An [52] US Cl. ..200/148 A, 200/150 G escape valve opens in the case of an excess of pressure [51] Int. Cl. ..H0lh 33/70 in one compartment to allow escape of pressure into [58] Field of Search ..200/148 A, 150 G the other compartment.

9 Claims, 3 Drawing Figures PMENTEDHAHSISB 9,733,452

SHEET 1 [1F 3 v PATENTED 3,733,452

SHEET 2 0F 3 FIG.2

PRESSURE EQUALIZATION MEANS BETWEEN COMPARTMENTS IN A PUF FER CIRCUIT INTERRUPTER The present invention concerns a circuit interrupter and more particularly a puffer-type fluid circuit interrupter comprising a gas-tight casing and a fixed intermediate partition which subdivides said casing into two compartments. The arc-extinguishing chamber formed by the first compartment contains a puffer mechanism and a pair of separable elongated contacts, and the second compartment contains a contact operating rod which passes through an orifice provided in the intermediate partition, as well as a current connecting device which cooperates with the elongated moving contact operating rod.

The known interrupters of this type are filled with a compressed extinguishing gas such as sulfur hexafluoride (SF6) which is circulated within the gas tight casing or enclosure for the blowing of an arc drawn between the contacts by the displacement of a puffer piston mechanically connected to the moving contact of the interrupter. The high insulating power of the gas in the casing permits relatively small distances of insulation, and it is known to house the shank of the moving contact, which constitutes the current feed conductor and the actuating rod of the movable contact in a compartment within said casing in order to effect the current collection of the moving contact, as well as the insulating of said actuating rod by the insertion of an insulating section within an insulating SP6 atmosphere.

An object of the invention is to provide a circuit interrupter in which the pressures in the two compart ments of the casing are balanced out rapidly after each contact opening.

The intermediate partition comprises an opening which can be closed by a closure valve. In the open position of the valve the two compartments freely communicate and the pressures rapidly equalize themselves, while in the closed position of the valve an excess pressure can be produced in the compartment forming the extinguishing chamber so as to cause a flow of gas into the arc forming zone.

The opening of the valve is caused at the end of the stroke of the opening movement of the interrupter by abutment means connected with the movable contact operating rod.

Another object of the invention is to provide a circuit interrupter in which any explosion of the casing under the effect of an accidental internal excess pressure is avoided by pressure exchange between the two compartments.

Another object of the invention is to provide a circuit interrupter with a gas-tight casing having a cover capable of automatically removing in case of substantial excess pressure.

Another object is to provide a circuit interrupter in which the filling of the two compartments of the casing may be made from a single orifice if one takes care to open the communication between the two compartments in order to facilitate the simultaneous evacation of the compartments without excessive wiredrawing of the gasses.

Other advantages and features of the invention will become evident from the following description of two embodiments of the invention shown in the accompanying drawings in which:

FIG. 1 is an axial cross-section of a circuit interrupter according to the present invention, shown in closed position FIG. 2 which is similar to FIG. 1, shows the circuit interrupter in open position FIG. 3 shows a modified type of the circuit interrupter.

In the figures, a tubular casing 10, for instance of synthetic material molded in a single block with two side arms 12, 14 which bear at their ends the terminals 16, 18 of the interrupter and surround the inlet and outlet conductors 20, 22 connected with the terminals 16, 18, is closed at its open base by a removable cover 24 which permits the insertion and mounting of the elements contained in the casing 10. A pair of elongated contacts is arranged coaxially in the casing 10, the stationary or semi-stationary contact 26 which is electrically connected to the conductor 22, protuding towards the inside of the casing 10 from the end 28 which is integral with the side wall. The movable contact 30 which is aligned with the stationary contact 26 terminates in an actuating or contact operating rod 32 which passes through an opening 34 provided in the removable cover 24 and cooperates with any control device (not shown) which is located outside the casing 10 and is capable of causing a sliding of the movable contact 30, by causing the separation or abutting of the contacts 26, 30. An insulating section 35 is inserted in the portion of the rod 32 within the casing 10. A bellows or diaphragm 36, rigidly connected to the rod 32 and to the cover 24, assures the sealing of the passage of the rod 32 through the opening 34. The cover 24 hermetically closes off the casing or enclosure 10, for instance by insertion of gaskets 38, and it is held in place by a shear washer partially embedded in a groove in the side wall of the enclosure 10 and having a protrusion resting against the cover 24.

A fixed intermediate transverse partition 42 is arranged within the enclosure 10 which subdivides the enclosure 10 into two compartments 44 and 46, one of which, 44, contains the shank of the movable contact 30 and the actuating rod 32, while the other compartment constitutes an extinction chamber for the arc which may be drawn between the contacts 26 and 30. The movable contact 30 is electrically connected to the conductor 20 by sliding collecting contact 48, housed in the compartment 44.

The intermediate partition 42 has an opening the edges of which constitute the seat for the closure member or valve 52 slidably mounted on the rod of the movable contact 30 which passes through it. A compression spring 54, inserted between the valve 52 and a stationary stop 56 urges the valve 52 against its seat into closed position in which the compartments 44 and 46 are isolated from each other. The valve 52 and the spring 54 are adapted to open automatically only in the case that a predetermined pressure threshold which is greater than the normal operating pressure is exceeded in the compartment 46.

To the movable contact 30 or the operating rod 32 is fastened a puffer piston 58 mounted for hermetic sliding in the enclosure 10 and having an orifice 60 for the escape of the compressed gages through the piston 58. The orifice 60 debouches within a nozzle 62 borne by the piston 58 and surrounding the contacts 26, 30 and which channels the blow or blast gases in a order to effect in known manner the extinction of the arc. The contacts 26 and 30 may be of any type.

The movable piston 58 and the stationary intermediate partition 42 define along with a section of the wall of the enclosure 10, a variable volume with exhaust orifice 60 in which the extinguishing gas is compressed by displacement of the puffer piston 58 in a direction towards the partition 42. The spring 54 is calibrated in such a manner as to oppose the opening of the valve 52 under the action of the excess pressures produced in the compartment 46 upon normal operation of the interrupter; In case of abnormal, accidental excess pressure, the valve 52 is nevertheless forced into open position so as to permit an escape of the gases into the compartment 44.

The valve 52 bears a collar 64 which protrudes towards the piston 58, the latter coming at the end of the opening stroke of the movable contact 30 against the collar 64 to carry it along in its movement and open the valve 52 and thus provide communication between the compartments 44 and 46. An orifice 66 for the connection of a pump or a source of gas is provided in the cover 24 and a plug 68 normally closes this opening.

It is needless to describe here in detail the operation of the puffer-gas blast circuit interrupter, as this is well known, and it is sufficient to state that the compressed gas which fills the hermetic enclosure 10, in particular sulfur hexafluoride (SP6) is expelled upon the opening of the interrupter by the piston 58 which moves with the contact 30, through the nozzle 62, so as to extinguish the are drawn between the contacts 26 and 30. In normal operation of the interrupter, the gas of the compartment 44 does not participate in the blasting of the arc. At the end of the opening stroke of the movable contact 30 the piston 58 strikes against the collar 64 of the valve 52 and pushes the latter in opposition to the action of the spring 54 into the open position causing the compartments 44 and 46 to communicate with each other. An equalization of the pressures between the compartments is thus effected after each break. Upon the starting of the closing stroke of the moving contact 30, the piston 58 in its displacement frees the collar 64 from the valve 52 and closes again under the action of the spring 54.

In case of an accidental excess pressure greater than the blasting pressure and which spreads out rapidly in the entire compartment 46, for instance in case of persistent arc, the valve 52 which is subjected to this excess pressure opens, allowing the overcompressed gas to escape into the compartment 44. If the expansion which results therefrom is insufficient and the pressure in the enclosure exceeds a certain threshold sufficient for the shearing of the washer 40, the latter frees the removable cover 24, connecting the enclosure 10 with the atmosphere. An explosion of the casing in thus avoided.

In order to fill the enclosure 10 with the compressed SP6 gas, it is advisable to remove the air contained in the compartments 44 and 46. This operation is easily effected if one is careful to bring the movable contact into open position in which the valve 52 is open, the air passing freely from the compartment 46 towards the compartment 44 and through the connecting orifice 66 to the vacuum pump (not shown). The time for placing under vacuum is thus substantially reduced.

Referring to FIG. 3, there will now be described a variant of the invention which makes it possible to establish communication between the compartments 44 and 46 which are separated by the partition 42, in a particularly simple manner in open position of the in terrupter. A groove 70 is provided in the outer part of the rod 32 so as to come to the level of the partition 42 in the open position of the movable contact. The axial length of the groove 70 is greater than the thickness of the partition 42 so as to protrude on both sides and bridge over the latter. The communication between the compartments 44 and 46 is established as soon as the groove 70 clears the edge of the partition 42. The com munication can obviously be produced by an axial conduit which debouches at two points spaced longitudinally on the periphery of the rod 32.

What is claimed is:

1. A puffer-type circuit interrupter, comprising;

a. an elongated enclosure for housing an arc extinguishing gas;

b. a partition wall means, fixedly connected to the elongated enclosure and having an aperture, for dividing the enclosure into first and second compartments;

c. separable contact means, in the first compartment,

for drawing an arc;

d. reciprocal contact operating means, traversing the second compartment and the partition wall means, for reciprocally operating the separable contact means;

e. a puffer means, in the first compartment, for directing a blast of gas into an are upon separation of the separable contact means; and

f. a closeable gas communication means, moveably connected to the partition wall means, for closingoff communication of the gas between the first and second compartments and for enabling the communication of the gas between the first and second compartments when the separable contact means are separated, thereby equalizing the pressures of the first and second compartments.

2. A circuit interrupter according to claim 1, wherein the closeable means comprises a valve which is resiliently biased towards the closed position thereof, and wherein the puffer means comprises means for engaging and opening the valve during the final separation movement of the reciprocal contact operating means.

3. A circuit interrupter according to claim 2, wherein the valve is biased by spring means biasing the valve towards the closed position thereof and wherein the spring means is calibrated to enable the opening of the valve in response to excessive pressure build-up in the first compartment.

4. A circuit interrupter according to claim 2, wherein the enclosure comprises a substantially tubular casing of insulating material; and wherein the separable contact means comprises a pair of aligned, elongated contacts disposed axially of the enclosure; and wherein the reciprocal contact operating means comprises an operating rod, having a portion of insulating material located in the second compartment, longitudinally aligned with the elongated contacts; and wherein the partition wall means has a central aperture, traversed by the operating rod which defines the passageway for communication of the gas.

5. A circuit-interrupter according to claim 4, wherein the valve comprises a spring biased, annular valve which surrounds the operating rod coaxially and wherein the valve is adapted to close the aperture.

6. A circuit interrupter according to claim 5, wherein one of the elongated contacts comprises a movable contact forming a unitary structure with the operating rod; and wherein the puffer means comprises a movable piston surrounding the unitary structure and secured thereto, said piston defining the means for engaging.

7. A circuit interrupter according to claim 1, wherein the separable contact means comprises an elongated movable contact; and wherein the reciprocal contact operating means comprises an operating rod aligned with the movable contact and forming a unitary rodlike structure therewith; and wherein the partition wall means has an aperture, traversed by the rod-like structhe locking means comprises a shear washer. 

1. A puffer-type circuit interrupter, comprising; a. an elongated enclosure for housing an arc extinguishing gas; b. a partition wall means, fixedly connected to the elongated enclosure and having an aperture, for dividing the enclosure into first and second compartments; c. separable contact means, in the first compartment, for drawing an arc; d. reciprocal contact operating means, traversing the second compartment and the partition wall means, for reciprocally operating the separable contact means; e. a puffer means, in the first compartment, for directing a blast of gas into an arc upon separation of the separable contact means; and f. a closeable gas communication means, moveably connected to the partition wall means, for closing-off communication of the gas between the first and second compartments and for enabling the communication of the gas between the first and second compartments when the separable contact means are separated, thereby equalizing the pressures of the first and second compartments.
 2. A circuit interrupter according to claim 1, wherein the closeable means comprises a valve which is resiliently biased towards the closed position thereof, and wherein the puffer means comprises means for engaging and opening the valve during the final separation movement of the reciprocal contact operating means.
 3. A circuit interrupter according to claim 2, wherein the valve is biased by spring means biasing the valve towards the closed position thereof and wherein the spring means is calibrated to enable the opening of the valve in response to excessive pressure build-up in the first compartment.
 4. A circuit interrupter according to claim 2, wherein the enclosure comprises a substantially tubular casing of insulating material; and wherein the separable contact means comprises a pair of aligned, elongated contacts disposed axially of the enclosure; and wherein the reciprocal contact operating means comprises an operating rod, having a portion of insulating material located in the second compartment, longitudinally aligned with the elongated contacts; and wherein the partition wall means has a central aperture, traversed by the operating rod which defines the passageway for communication of the gas.
 5. A circuit-interrupter according to claim 4, wherein the valve comprises a spring biased, annular valve which surrounds the operating rod coaxially and wherein the valve is adapted to close the aperture.
 6. A circuit interrupter according to claim 5, wherein one of the elongated contacts comprises a movable contact forming a unitary structure with the operating rod; and wherein the puffer means comprises a movable piston surrounding the unitary structure and secured thereto, said piston defining the means for engaging.
 7. A circuit interrupter according to claim 1, wherein the separable contact means comprises an elongated movable contact; and wherein the reciprocal contact operating means comprises an operating rod aligned with the movable contact and forming a unitary rod-like structure therewith; and wherein the partition wall means has an aperture, traversed by the rod-like structure and defining the passageway for communication of the gas, said rod-like structure being shaped to obturate the aperture except during the final separation movement of the rod-like structure.
 8. A circuit interrupter according to claim 1, wherein the second compartment comprises a removable wall portion having a releasable locking means to hold the removable wall portion in the position and to automatically unlock the removable wall portion in response to excessive pressure build-up in the second compartment.
 9. A circuit interrupter according to claim 8, wherein the locking means comprises a shear washer. 